silver solder

Hi everyone,

Can anyone give me a rough idea please of the amount of silver solder that I am likely to need to construct a medium sized boiler for a 3.5 gauge loco. I imagine that this is a bit of a how long is a piece of string question but a rough idea would be helpful as it represents quite a big investment.

with thanks Nigel

Not just amount but you will need different types ( melting points) through the stages of construction.

I am sure someone who has made a boiler for 3.5" gauge will come along with an answer. You do not have to buy it all at once of course.

A regards whether or not you actually need differing melting points will depend upon your skills and the actual assembly. It is of course possible to only use one grade.

For a very rough idea:

Measure or calculate total joint lengths and that will give approximate length of 1mm diameter silver solder that you require. Don't forget 'dabs' around fasteners, rings around stays & bushes, etc.,

Actual amount used will depend on fit of joints, depth of joints, your skill-level, etc., etc. You can always add a contingency. I s'pose that knowing the gap and depth of the joints one could calculate an 'exact' minimum volume of solder required, but .............!!

'Fraid that I cannot give you an actual amount used, as, whilst I have made a couple of copper boilers, I didn't keep a record of the amounts of silver solder consumed as I tend to buy 'quite a bit' for all kinds of silver-soldering jobs and seem to just use it up without any conscious consideration!

Regards,

Phil.

Very tricky question - an expert would likely do it in 8 sticks or less, all same temp. A novice might never achieve a complete boiler depending on how good the pre soldered jointing surfaces are but if good start with 20 sticks and tenicity flux. My joining surfaces are usually very accurate but the odd thou here and there bigger can result in a lot more solder being used to compensate. If youve got a big burner a couple of heat grades is a good ldea, if youve got oxy-prop then just the low temp will be fine (55% silver). A few trade tips - put a big sign up saying do not disturb, have a drink and a pee before you start and dont rush it. Apply the flux thickly and it wont burn out quickly. Hope this helps

Nigel@pendlesteam

Would they be big sticks or little sticks Fizzy? 0.7, 1.5, 2 or 2.5 dia?

thanks guys I am a little closer to estimating a budget !

Hi Nigel,

As a rough rule of thumb I use about the same amount of silver solder in cost of the copper for the boiler. This would be for boilers with all silver soldered firebox stays. There are only a few grades of silver solder recommended for boiler work post the cadmium ban, that have the required ductility etc.

There are lots of reasons why people have problems silver soldering up miniature loco boilers, and one of these is meaness in applying the silver solder.

Cheers,

Julian

Oops - Well spotted Jason - I use 1.5mm x 500mm only at this size - standard rods from CUP (and others). Ive never heard the rule of thumb Julian refers to but its a very good ball park estimate.

Hi Nigel,

Those who have attended the "CuP Alloys Roadshow" over the years will know that we have been banging on since the start about achieving the minimum spend on silver solder. That is best achieved by using it properly and hence efficiently.

Take a little time to appreciate what you are trying to do, why and how to do it it.

Silver soldering is a very simple process but skillful. Stick to the principles and you will be successful. You will produce strong leak-free joints first time , every time and use the minimum amount of this expensive filler metal. Deviate from them and you will not be and the process becomes complicated and difficult.

There have been many a boiler made that should have been hallmarked.

Avoid fillets, examine your joint designs, heating technique and alloy placement.

How much alloy will you use?

Are you planning to use two alloys of differing melting temperature?

Use the thinnest rod practical.

Do not skimp on flux.

You will find all the information you require on the website and in our publications. Call 01909 547248 for a chat. There is the widest range of materials, sizes and 48 years experience in the silver soldering business.

Can't get that on ebay! Or anywhere else for that matter!

Regards

Keith

Fizzy mentioned a very important point - but only in passing and it could be easily missed alongside his other good advice....

But use a "Tenacity" type flux - something like HT5 (if you purchase it from CuP)

Regards,

IanT